- #1

miyayeah

- 27

- 0

## Homework Statement

The question is as follows: A 50kg ice skater is gliding along the ice, heading due north at 4.0m/s. The ice has a small coefficient of static friction, to prevent the skater from slipping sideways, but kinetic friction =0. Suddenly, a wind from the northeast exerts a force of 4N on the skater. Use work and energy to find the skater's speed after gliding 100m in this wind.

## Homework Equations

W= F ⋅ d

W= ΔKE = 1/2 mv

_{f}

^{2}-1/2 mv

_{i}

^{2}

## The Attempt at a Solution

W= F ⋅ d = (sin45)(4N)(100m) = 282.842712 J

In this step I assumed the angle to be 45 degrees because we are trying to find the y component of the force. (Since there is no movement sideways and speed is not affected by the sideway movement)

I used the above value of work in the next step. I rearranged the formula below to get final velocity.

W= ΔKE = 1/2 mv

_{f}

^{2}-1/2 mv

_{i}

^{2}

v

_{f}= √[(2W+mv

_{i}

^{2})/m]

Plugging in the values from the question gave me 5.2 m/s. The correct answer was 2.2m/s.

Any help would be much appreciated!